1. Field of the Invention
The present invention relates to a transfer sheet conveying device for use in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and more particularly to a transfer sheet conveying device forming a slack in a transfer sheet by impinging the transfer sheet driven by a pair of transfer sheet conveying rollers upon a pair of registration rollers which are at a standstill.
2. Discussion of the Background
In an image forming apparatus, a pair of registration rollers are arranged in the vicinity of an upstream side (in a sheet conveying direction) of a photoconductive element. A leading edge of a transfer sheet conveyed by a pair of transfer sheet conveying rollers (hereinafter referred to as pair of grip rollers) impinges upon a pair of registration rollers, which are at a standstill, and thereby a slack is formed in the transfer sheet, i.e., the transfer sheet is bowed, to correct a skew of the transfer sheet.
The transfer sheet, the skew of which is corrected, is then conveyed by the pair of registration rollers to a transfer section in synchronization with a visible image (a toner image) formed on the photoconductive drum. The visible image is transferred onto the transfer sheet by a transfer charger and a transfer roller or a transfer belt at the transfer section.
In forming a slack in a transfer sheet between the pair of grip rollers and the pair of registration rollers, when the transfer sheet is relatively thick and rigid, the pair of grip rollers may be rotated in an opposite direction so that the transfer sheet is conveyed by a return force caused by the resilience of the slack in the transfer sheet. Thereby, a proper slack in a transfer sheet may not be formed.
A one-way rotating clutch has been employed in the pair of grip rollers to obviate the above-described inconvenience. The one-way rotating clutch is also configured to idle the pair of grip rollers when the pair of registration rollers conveys a transfer sheet so as to reduce a transportation load imposed on the pair of grip rollers.
When a transfer sheet is jammed and is caught by the pair of grip rollers, the jammed sheet can be easily removed by being pulled out from a downstream side of the pair of grip rollers because the pair of grip rollers are idled. However, when the jammed sheet is removed from an upstream side of the pair of grip rollers, a substantial force is required to pull out the jammed sheet because the pair of grip rollers are locked by the one-way rotating clutch. Further, the transfer sheet may tear, and a piece of torn transfer sheet may remain inside the apparatus, causing another transfer sheet to jam when the next transfer sheet is conveyed.
The present invention has been made in view of the above-discussed and other problems and addresses the above-discussed and other problems.
The present invention advantageously provides a novel transfer sheet conveying device with an improved ability to remove a jammed sheet while securing an adequate slack in a transfer sheet, thereby insuring high transfer sheet conveying quality.
According to an embodiment of the present invention, a transfer sheet conveying device for use in an image forming apparatus, comprises a pair of transfer sheet conveying rollers to convey a transfer sheet and a pair of registration rollers arranged at a downstream side of said pair of transfer sheet conveying rollers. The pair of transfer sheet conveying rollers can convey and impinge the transfer sheet upon said pair registration rollers so as to form a slack in the transfer sheet. A one-way rotating clutch mounts the pair of transfer sheet conveys rollers such that they idle in a transfer sheet conveying direction and have a predetermined torque in an opposite direction thereto, wherein the one-way rotating clutch is itself mounted to rotate in the opposite direction in response to a force in the opposite direction. As a result, a jammed transfer sheet can easily be removed.
Other objects, features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.